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Bartsch CJ, Jacobs JT, Mojahed N, Qasem E, Smith M, Caldwell O, Aaflaq S, Nordman JC. Visualizing traumatic stress-induced structural plasticity in a medial amygdala pathway using mGRASP. Front Mol Neurosci 2023; 16:1313635. [PMID: 38098941 PMCID: PMC10720331 DOI: 10.3389/fnmol.2023.1313635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 11/07/2023] [Indexed: 12/17/2023] Open
Abstract
Traumatic stress has been shown to contribute to persistent behavioral changes, yet the underlying neural pathways are not fully explored. Structural plasticity, a form of long-lasting neural adaptability, offers a plausible mechanism. To scrutinize this, we used the mGRASP imaging technique to visualize synaptic modifications in a pathway formed between neurons of the posterior ventral segment of the medial amygdala and ventrolateral segment of the ventromedial hypothalamus (MeApv-VmHvl), areas we previously showed to be involved in stress-induced excessive aggression. We subjected mice (7-8 weeks of age) to acute stress through foot shocks, a reliable and reproducible form of traumatic stress, and compared synaptic changes to control animals. Our data revealed an increase in synapse formation within the MeApv-VmHvl pathway post-stress as evidenced by an increase in mGRASP puncta and area. Chemogenetic inhibition of CaMKIIα-expressing neurons in the MeApv during the stressor led to reduced synapse formation, suggesting that the structural changes were driven by excitatory activity. To elucidate the molecular mechanisms, we administered the NMDAR antagonist MK-801, which effectively blocked the stress-induced synaptic changes. These findings suggest a strong link between traumatic stress and enduring structural changes in an MeApv-VmHvl neural pathway. Furthermore, our data point to NMDAR-dependent mechanisms as key contributors to these synaptic changes. This structural plasticity could offer insights into persistent behavioral consequences of traumatic stress, such as symptoms of PTSD and social deficits.
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Affiliation(s)
| | | | | | | | | | | | | | - Jacob C. Nordman
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, IL, United States
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Murthy BKB, Somatakis S, Ulivi AF, Klimmt H, Castello-Waldow TP, Haynes N, Huettl RE, Chen A, Attardo A. Arc-driven mGRASP highlights CA1 to CA3 synaptic engrams. Front Behav Neurosci 2023; 16:1072571. [PMID: 36793796 PMCID: PMC9924068 DOI: 10.3389/fnbeh.2022.1072571] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/29/2022] [Indexed: 02/03/2023] Open
Abstract
Subpopulations of neurons display increased activity during memory encoding and manipulating the activity of these neurons can induce artificial formation or erasure of memories. Thus, these neurons are thought to be cellular engrams. Moreover, correlated activity between pre- and postsynaptic engram neurons is thought to lead to strengthening of their synaptic connections, thus increasing the probability of neural activity patterns occurring during encoding to reoccur at recall. Therefore, synapses between engram neurons can also be considered as a substrate of memory, or a synaptic engram. One can label synaptic engrams by targeting two complementary, non-fluorescent, synapse-targeted GFP fragments separately to the pre- and postsynaptic compartment of engram neurons; the two GFP fragments reconstitute a fluorescent GFP at the synaptic cleft between the engram neurons, thereby highlighting synaptic engrams. In this work we explored a transsynaptic GFP reconstitution system (mGRASP) to label synaptic engrams between hippocampal CA1 and CA3 engram neurons identified by different Immediate-Early Genes: cFos and Arc. We characterized the expression of the cellular and synaptic labels of the mGRASP system upon exposure to a novel environment or learning of a hippocampal-dependent memory task. We found that mGRASP under the control of transgenic ArcCreERT2 labeled synaptic engrams more efficiently than when controlled by viral cFostTA, possibly due to differences in the genetic systems rather than the specific IEG promoters.
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Affiliation(s)
- B. K. B. Murthy
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany
| | - S. Somatakis
- Max Planck Institute of Psychiatry, Munich, Germany
| | - A. F. Ulivi
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Max Planck Institute of Psychiatry, Munich, Germany
| | - H. Klimmt
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany
| | | | - N. Haynes
- Max Planck Institute of Psychiatry, Munich, Germany
| | - R. E. Huettl
- Max Planck Institute of Psychiatry, Munich, Germany
| | - A. Chen
- Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany,Weizmann Institute of Science, Rehovot, Israel
| | - Alessio Attardo
- Leibniz Institute for Neurobiology, Magdeburg, Germany,Graduate School of Systemic Neurosciences, Munich, Germany,Max Planck Institute of Psychiatry, Munich, Germany,International Max Planck Research School for Translational Psychiatry, Munich, Germany,*Correspondence: Alessio Attardo,
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Ramsey LA, Koya E, van den Oever MC. Editorial: Neuronal ensembles and memory engrams: Cellular and molecular mechanisms. Front Behav Neurosci 2023; 17:1157414. [PMID: 36926583 PMCID: PMC10011704 DOI: 10.3389/fnbeh.2023.1157414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 02/13/2023] [Indexed: 03/08/2023] Open
Affiliation(s)
- Leslie A Ramsey
- Behavioral Neuroscience Research Branch Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health (NIH), Baltimore, MD, United States
| | - Eisuke Koya
- School of Psychology, Sussex Neuroscience, University of Sussex, Falmer, United Kingdom
| | - Michel C van den Oever
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
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Kwon O, Feng L, Druckmann S, Kim J. Schaffer Collateral Inputs to CA1 Excitatory and Inhibitory Neurons Follow Different Connectivity Rules. J Neurosci 2018; 38:5140-52. [PMID: 29728449 DOI: 10.1523/JNEUROSCI.0155-18.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 03/12/2018] [Accepted: 04/19/2018] [Indexed: 11/21/2022] Open
Abstract
Neural circuits, governed by a complex interplay between excitatory and inhibitory neurons, are the substrate for information processing, and the organization of synaptic connectivity in neural network is an important determinant of circuit function. Here, we analyzed the fine structure of connectivity in hippocampal CA1 excitatory and inhibitory neurons innervated by Schaffer collaterals (SCs) using mGRASP in male mice. Our previous study revealed spatially structured synaptic connectivity between CA3 and CA1 pyramidal cells (PCs). Surprisingly, parvalbumin-positive interneurons (PVs) showed a significantly more random pattern spatial structure. Notably, application of Peters' rule for synapse prediction by random overlap between axons and dendrites enhanced structured connectivity in PCs, but, by contrast, made the connectivity pattern in PVs more random. In addition, PCs in a deep sublayer of striatum pyramidale appeared more highly structured than PCs in superficial layers, and little or no sublayer specificity was found in PVs. Our results show that CA1 excitatory PCs and inhibitory PVs innervated by the same SC inputs follow different connectivity rules. The different organizations of fine scale structured connectivity in hippocampal excitatory and inhibitory neurons provide important insights into the development and functions of neural networks.SIGNIFICANCE STATEMENT Understanding how neural circuits generate behavior is one of the central goals of neuroscience. An important component of this endeavor is the mapping of fine-scale connection patterns that underlie, and help us infer, signal processing in the brain. Here, using our recently developed synapse detection technology (mGRASP and neuTube), we provide detailed profiles of synaptic connectivity in excitatory (CA1 pyramidal) and inhibitory (CA1 parvalbumin-positive) neurons innervated by the same presynaptic inputs (CA3 Schaffer collaterals). Our results reveal that these two types of CA1 neurons follow different connectivity patterns. Our new evidence for differently structured connectivity at a fine scale in hippocampal excitatory and inhibitory neurons provides a better understanding of hippocampal networks and will guide theoretical and experimental studies.
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Rah JC, Feng L, Druckmann S, Lee H, Kim J. From a meso- to micro-scale connectome: array tomography and mGRASP. Front Neuroanat 2015; 9:78. [PMID: 26089781 PMCID: PMC4454886 DOI: 10.3389/fnana.2015.00078] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 05/21/2015] [Indexed: 11/21/2022] Open
Abstract
Mapping mammalian synaptic connectivity has long been an important goal of neuroscience because knowing how neurons and brain areas are connected underpins an understanding of brain function. Meeting this goal requires advanced techniques with single synapse resolution and large-scale capacity, especially at multiple scales tethering the meso- and micro-scale connectome. Among several advanced LM-based connectome technologies, Array Tomography (AT) and mammalian GFP-Reconstitution Across Synaptic Partners (mGRASP) can provide relatively high-throughput mapping synaptic connectivity at multiple scales. AT- and mGRASP-assisted circuit mapping (ATing and mGRASPing), combined with techniques such as retrograde virus, brain clearing techniques, and activity indicators will help unlock the secrets of complex neural circuits. Here, we discuss these useful new tools to enable mapping of brain circuits at multiple scales, some functional implications of spatial synaptic distribution, and future challenges and directions of these endeavors.
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Affiliation(s)
- Jong-Cheol Rah
- Korea Brain Research InstituteDaegu, South Korea
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu, South Korea
| | - Linqing Feng
- Center for Functional Connectomics, Korea Institute of Science and Technology (KIST)Seoul, South Korea
| | - Shaul Druckmann
- Janelia Farm Research Campus, Howard Hugh Medical InstituteAshburn, VA, USA
| | - Hojin Lee
- Center for Functional Connectomics, Korea Institute of Science and Technology (KIST)Seoul, South Korea
- Neuroscience Program, University of Science and TechnologyDaejeon, South Korea
| | - Jinhyun Kim
- Center for Functional Connectomics, Korea Institute of Science and Technology (KIST)Seoul, South Korea
- Neuroscience Program, University of Science and TechnologyDaejeon, South Korea
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